Prevalences of Shiga toxin subtypes and selected other virulence factors among Shiga-toxigenic Escherichia coli strains isolated from fresh produce.
Appl Environ Microbiol
; 79(22): 6917-23, 2013 Nov.
Article
en En
| MEDLINE
| ID: mdl-23995936
ABSTRACT
Shiga-toxigenic Escherichia coli (STEC) strains were isolated from a variety of fresh produce, but mostly from spinach, with an estimated prevalence rate of 0.5%. A panel of 132 produce STEC strains were characterized for the presence of virulence and putative virulence factor genes and for Shiga toxin subtypes. About 9% of the isolates were found to have the eae gene, which encodes the intimin binding protein, and most of these belonged to known pathogenic STEC serotypes, such as O157H7 and O26H11, or to serotypes that reportedly have caused human illness. Among the eae-negative strains, there were three O113H21 strains and one O91H21 strain, which historically have been implicated in illness and therefore may be of concern as well. The ehxA gene, which encodes enterohemolysin, was found in â¼60% of the isolates, and the saa and subAB genes, which encode STEC agglutinating adhesin and subtilase cytotoxin, respectively, were found in â¼30% of the isolates. However, the precise roles of these three putative virulence factors in STEC pathogenesis have not yet been fully established. The stx1a and stx2a subtypes were present in 22% and 56%, respectively, of the strains overall and were the most common subtypes among produce STEC strains. The stx2d subtype was the second most common subtype (28% overall), followed by stx2c (7.5%), and only 2 to 3% of the produce STEC strains had the stx2e and stx2g subtypes. Almost half of the produce STEC strains had only partial serotypes or were untyped, and most of those that were identified belonged to unremarkable serotypes. Considering the uncertainties of some of these Stx subtypes and putative virulence factors in causing human illness, it is difficult to determine the health risk of many of these produce STEC strains.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Toxinas Shiga
/
Proteínas de Escherichia coli
/
Factores de Virulencia
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Escherichia coli Shiga-Toxigénica
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Microbiología de Alimentos
/
Proteínas Hemolisinas
Tipo de estudio:
Prognostic_studies
/
Risk_factors_studies
Idioma:
En
Revista:
Appl Environ Microbiol
Año:
2013
Tipo del documento:
Article
País de afiliación:
Estados Unidos